diff --git a/Makefile.include b/Makefile.include
index 7b551e44d8..e62042994d 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -203,13 +203,11 @@ endif
 
 # Fail on warnings. Can be overridden by `make WERROR=0`.
 WERROR ?= 1
-export WERROR
 ifeq ($(WERROR),1)
   CFLAGS += -Werror
 endif
 
 WPEDANTIC ?= 0
-export WPEDANTIC
 ifeq ($(WPEDANTIC),1)
   CFLAGS += -Wpedantic
 endif
@@ -295,7 +293,6 @@ ifeq (,$(TOOLCHAIN))
 override TOOLCHAIN := gnu
 endif
 
-export TOOLCHAIN
 
 # default toolchain prefix, defaults to target triple followed by a dash, you
 # will most likely not need to touch this.
diff --git a/dist/tools/buildsystem_sanity_check/check.sh b/dist/tools/buildsystem_sanity_check/check.sh
index 011db079b4..f3932d4bdd 100755
--- a/dist/tools/buildsystem_sanity_check/check.sh
+++ b/dist/tools/buildsystem_sanity_check/check.sh
@@ -83,6 +83,10 @@ UNEXPORTED_VARIABLES+=('PORT[ ?=:]' 'PORT$')
 EXPORTED_VARIABLES_ONLY_IN_VARS=()
 EXPORTED_VARIABLES_ONLY_IN_VARS+=('CPU_ARCH')
 EXPORTED_VARIABLES_ONLY_IN_VARS+=('CPU_FAM')
+EXPORTED_VARIABLES_ONLY_IN_VARS+=('TOOLCHAIN')
+EXPORTED_VARIABLES_ONLY_IN_VARS+=('WERROR')
+EXPORTED_VARIABLES_ONLY_IN_VARS+=('WPEDANTIC')
+
 check_not_exporting_variables() {
     local patterns=()
     local pathspec=()
diff --git a/makefiles/vars.inc.mk b/makefiles/vars.inc.mk
index f2c5fb21b0..88263a47cb 100644
--- a/makefiles/vars.inc.mk
+++ b/makefiles/vars.inc.mk
@@ -44,6 +44,7 @@ export FEATURES_PROVIDED     # List of provided features by the board
 export FEATURES_OPTIONAL     # List of nice to have features
 # TOOLCHAINS_SUPPORTED       # List of supported toolchains by an MCU (gnu/llvm/...).
 # TOOLCHAINS_BLACKLISTED     # List of unspported toolchains for a module or an application.
+export TOOLCHAIN             # Base build toolchain, i.e. GNU or LLVM
 
 export TARGET_ARCH           # The target platform name, in GCC triple notation, e.g. "arm-none-eabi", "i686-elf", "avr"
 export PREFIX                # The prefix of the toolchain commands, usually "$(TARGET_ARCH)-", e.g. "arm-none-eabi-" or "msp430-".
@@ -71,6 +72,7 @@ export SIZE                  # The command to read to size of the ELF sections.
 export SIZEFLAGS             # The optional size flags.
 export UNDEF                 # Object files that the linker must include in the ELFFILE even if no call to the functions or symbols (ex: interrupt vectors).
 export WERROR                # Treat all compiler warnings as errors if set to 1 (see -Werror flag in GCC manual)
+export WPEDANTIC             # Issue all (extensive) compiler warnings demanded by strict C/C++
 
 export GITCACHE              # path to git-cache executable
 export GIT_CACHE_DIR         # path to git-cache cache directory